A new study has shown that eyes could prove to be a potential gateway to identify whether or not a person has Alzheimer's disease.
Researchers from University of California, Irvine have found that retinas in mice genetically altered to have Alzheimer's undergo changes similar to those that occur in the brain - most notably the accumulation of amyloid plaque lesions.
Moreover, when Alzheimer's therapies are tested in such mice, retinal changes that result might predict how the treatments will work in humans better than changes in mouse brain tissue.
"It's important to discover the pathological changes before an Alzheimer's patient dies," said Zhiqun Tan, a UCI neuroscientist leading the research.
"Brain tissue isn't transparent, but retinas are. I hope in the future we'll be able to diagnose the disease and track its progress by looking into the eyes," Tan added.
Tan and colleagues analysed the retinas of Alzheimer's mice that had been treated with immunotherapy.
Vaccinated mice performed better on learning and memory tests than untreated mice, and their brains had fewer plaque lesions.
Similarly, retinas in the treated mice had fewer lesions than in untreated mice. However, the treated mice's retinas had worse inflammation and vascular changes associated with Alzheimer's than did their brains.
When immunotherapy was tested in humans, inflammation of brain tissue occurred similar to that observed in the mice retinas.
"This tells us the retina may be more sensitive at reflecting changes in the human brain," Tan added.
The study appears in The American Journal of Pathology.